Cockroaches are common insect pests, infesting residential homes and industrial buildings and causing huge damage. Various elimination methods are used for cockroaches. However, their nests are very close to human activity, which limits the use of insecticides. In addition, cockroaches have a habit of hiding in narrow crevices and they are very fertile. Consequently, conventional insect traps or poisoned baits are not effective enough to eliminate cockroaches. Recent studies have revealed much about pheromones of cockroaches, and use of the pheromones for cockroach control has been investigated (Patent Literature 1, 2 and 3). Pheromones are chemicals secreted by organisms and are capable of acting on members of the same species. A small amount of pheromones is known to exhibit strong activity such as attraction activity.
Insect pheromones include sex pheromones and aggregation pheromones. Sex pheromones are pheromones that are secreted and released by an individual to attract the opposite sex. Aggregation pheromones are semiochemicals that trigger aggregation of members of the same species, excluding sex pheromones. That is, aggregation pheromones are chemicals that act on individuals regardless of males or females, also act on larvae, which have no reproductive ability.
The term aggregation pheromone was first used for the German cockroach. The German cockroach secretes pheromones from the end of the abdomen to mark a shelter. Pheromones are also present on the surface of the insect's body, allowing them to distinguish the individuals of the same species. The aggregation pheromones of the German cockroach include attractant pheromones such as 1-dimethylamino-2-methyl-2-propanol, which acts as a scent, and also include arrestant pheromones (arrestants), which are contact chemicals. Some of the components of the pheromones have been identified (Non-Patent Literature 1). The Blaberus cockroach (Blaberus craniifer) secretes aggregation pheromones from the mandibular gland in the head. Several substances with attraction activity, such as undecane, tetradecane and ethylcaproic acid, have been identified from the scent components collected with activated carbon.
Cockroach pheromones as described above are expected to serve as attractants in insect traps and poisoned baits, and thereby to increase the cockroach controlling effect. Conventionally known attractants, such as periplanones, bornyl acetate and terpenoids, lack long-lasting effect. In some cases, these conventional attractants may be turned into the opposite type of compounds serving as repellents. Thus the conventional attractants are unsatisfactory in practice. Sex pheromones are effective only for adults of the opposite sex. For these reasons, there was a growing demand for the identification and the use of cockroach aggregation pheromones that are effective for all individuals, regardless of larvae or adults, or females or males.